In a typical roaming situation a user always registers to his home network e.g. in Finland. If clients of other operators want to contact the user, the traffic transfers via the home network. Thus in an unwanted situation where the user is visiting in a visited network e.g. in Australia, the traffic transfers from Australia to Finland and back to Australia instead of a situation where the traffic stays in Australia. Especially incoming real time services like a VoIP (Voice over Internet Protocol) service suffers dramatically from this problem.